I can buy either of the above used for the same amount and same condition, so which to choose?

I am leaning towards the Metz because of the small fill-light that can be used when bouncing the main light. Also I can update the Metz to work with future bodies.

Pentax seems to have better off-shoe capabilities though and it is a Pentax, same as the camera which maybe/maybe not could be an argument in itself.

My main use will be inside snapshots and maybe some photoshoots with family/friends, but nothing fancy, probably just some bouncing on-camera or a simple radiotrigger setup in the future.

Thanks in advance!

For what it's worth; I originally purchased a Pentax AF 360 for augmentation of the body flash mostly for indoor use (and I was attracted to the features it added). Evolved into shooting live band performance and subsequently found the Pentax unit became overheated with rapid firing over extended periods of time (the length of the set) and would become erratic. Purchased a Metz 58 and when used in the same environment, not a minute's trouble, fires without fail. I have used the Metz update feature and works with all of my Pentax cameras. @

I have both the Yongnuo and the Pentax 540. They are both great flashes and very close in power output. The Pentax does have HSS capabilities and the Yongnuo does have a metal mount. They both have similar recycle times. I have heard many good things about the Metz. I don't think you would go wrong with any of the three.

I have the Metz, every feature shines, and it has never failed. I have read stories about the Pentax overheating more than once. The Metz is not great for close up work though, have to go intensively into its menu for that possiblity. Perfect on exposure and completely overrideable when working within its boundaries, near and far.